How heavy are some of your Basses? There is constant reference to "lugging it round" as though it were a ton weight. It's a Bass for goodness sake! As to the "I can change a string in 0.5 seconds" --not very helpful if a crappily soldered joint falls off in the middle of a song, is it? Happened once to me, after a "Technician" had replaced a pick-up. (That was a story in itself, because the pick-up started crackling loudly in the middle of the set). On both occasions, I grabbed my spare, and kept going. I have had expensive batteries die quickly and annoyingly in my Radio gear after I had just replaced them, (rechargeables as well) crackly jack sockets, snapped a string (once) beer splashed on the Bass during a Bar fight, and various other mishaps over the (too) many years I have been playing. EVERY time, I grabbed for the spare, finished the set, and got paid. Sometimes I even got congratulated for "not missing a beat", or "not dropping the band in it". Carry a spare. It WILL happen to you sometime. You can guarantee it. If it hasn't yet, you've been lucky, but rest assured it will!